Fabrication tools for exerting normal forces on feedstock

ABSTRACT

The present invention relates to tooling and methods for disposing, coating, building up, repairing, or otherwise modifying the surface of a metal substrate using frictional heating and compressive loading of a consumable metal material against the substrate. Embodiments of the invention include friction-based fabrication tooling comprising a non-consumable member with a throat and a consumable member disposed in the throat, wherein the throat is operably configured such that during rotation of the non-consumable member at a selected speed, the throat exerts normal forces on and rotates the consumable member at the selected speed; and comprising means for dispensing the consumable member through the throat and onto a substrate using frictional heating and compressive loading. Embodiments of the invention also include fabrication methods using the tools described herein.

STATEMENT OF GOVERNMENT INTEREST

This invention was supported by the U.S. Office of Naval Research underContract No. N00014-05-1-0099. The U.S. Government has certain rights inthis invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. application Ser. No. 12/987,588,filed Jan. 10, 2011; U.S. application Ser. No. 12/792,655, filed Jun. 2,2010; U.S. application Ser. No. 11/527,149, filed Sep. 26, 2006; U.S.Provisional Application No. 60/720,521, filed Sep. 26, 2005; U.S.Provisional Application No. 61/293,543, filed Jan. 8, 2010; U.S.application Ser. Nos. 13/442,285 and 13/442,201, filed Apr. 9, 2012;U.S. Provisional Application Nos. 61/472,928 and 61/472,918, filed Apr.7, 2011, and 61/473,221, filed Apr. 8, 2011, the disclosures of each ofwhich is hereby incorporated by reference herein in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to tools and methods for disposing,coating, repairing, or otherwise modifying the surface of a metalsubstrate using frictional heating and compressive loading of aconsumable metal against the substrate. Embodiments of the inventioninclude friction-based fabrication tooling comprising a non-consumablemember with a throat and a consumable member disposed in the throat,wherein the throat is operably configured such that during rotation ofthe non-consumable member at a selected speed, the throat exerts normalforces on and rotates the consumable member at the selected speed; andcomprising means for dispensing the consumable member through the throatand onto a substrate using frictional heating and compressive loading.

2. Description of Related Art

Conventional coating techniques, such as flame spray, high-velocityoxygen fuel (HVOF), detonation-gun (D-Gun), wire arc and plasmadeposition, produce coatings that have considerable porosity,significant oxide content and discrete interfaces between the coatingand substrate. Typically, these coating processes operate at relativelyhigh temperatures and melt/oxidize the material as it is deposited ontothe substrate. Such conventional techniques are not suitable forprocessing many types of substrates and coating materials, such asnanocrystalline materials due to the grain growth and loss of strengthresulting from the relatively high processing temperatures.

An alternative deposition process available is referred to as cold spraytype depositing. Such techniques typically involve a relativelylow-temperature thermal spray process in which particles are acceleratedthrough a supersonic nozzle. These techniques, however, may berelatively expensive and/or generally incapable of processing highaspect ratio particles, such as nanocrystalline aluminum powder producedby cryomilling. As a result, products prepared using cold spraytechniques typically contain oxide impurities.

In light of these drawbacks, improvements in coating depositiontechniques are highly desired. Indeed, there is a specific need forfriction-based fabrication tools capable of depositing coatings onsubstrates efficiently and in a simple manner, which result in highquality adhesions between the substrate and coating and high strengthproducts having an increased resistance to failure.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a friction-basedfabrication tool comprising: a non-consumable body formed from materialcapable of resisting deformation when subject to frictional heating andcompressive loading and a throat defining a passageway lengthwisethrough the body and comprising means for exerting normal forces on amaterial in the throat during rotation of the body.

Specific embodiments of the invention include a friction-basedfabrication tool comprising: a non-consumable member having a body and athroat; wherein the throat is shaped to exert a normal force on aconsumable coating material disposed therein for imparting rotation tothe coating material from the body when rotated at a speed sufficientfor imposing frictional heating of the coating material against asubstrate; wherein the body is operably connected with means fordispensing and compressive loading of the coating material from thethroat onto the substrate and with means for rotating and translatingthe body relative to the substrate; wherein the body comprises a surfacefor trapping coating material loaded on the substrate in a volumebetween the body and the substrate and for forming and shearing asurface of a coating on the substrate.

Other specific embodiments include friction-based fabrication toolscomprising: (a) a spindle member comprising a hollow interior forhousing a coating material disposed therein prior to deposition on asubstrate; wherein the interior of the spindle is shaped to exert anormal force on the coating material disposed therein for rotating thecoating material during rotation of the spindle; (b) means, in operablecommunication with the spindle, for dispensing and compressive loadingof the coating material from the spindle onto the substrate and withmeans for rotating and translating the spindle relative to thesubstrate; and wherein the spindle comprises a shoulder surface with aflat surface geometry or a surface geometry with structure for enhancingmechanical stirring of the loaded coating material, which shouldersurface is operably configured for trapping the loaded coating materialin a volume between the shoulder and the substrate and for forming andshearing a surface of a coating on the substrate.

In some embodiments, the means for exerting normal forces on a materialin the throat during rotation of the body may be a throat having anon-circular cross-sectional shape. Additionally, any filler materialmay be used as the coating material, including consumable solid, powder,or powder-filled tube type coating materials. In the case of powder-typecoating material, the powder can be loosely or tightly packed within theinterior throat of the tool, with normal forces being more efficientlyexerted on tightly packed powder filler material. Packing of the powderfiller material can be achieved before or during the coating process.

Further provided are tooling configurations comprising any configurationdescribed in this application, or any configuration needed to implementa method according to the invention described herein, combined with aconsumable coating material member. Thus, tooling embodiments of theinvention include a non-consumable portion (resists deformation underheat and pressure) alone or together with a consumable coating materialor consumable filler material (eg, such consumable materials includethose that would deform, melt, or plasticize under the amount of heatand pressure the non-consumable portion is exposed to).

Another aspect of the present invention is to provide a method offorming a surface layer on a substrate, such as repairing a marredsurface, building up a surface to obtain a substrate with a differentthickness, joining two or more substrates together, or filling holes inthe surface of a substrate. Such methods can comprise depositing acoating material on the substrate with tooling described in thisapplication, and optionally friction stirring the deposited coatingmaterial, eg, including mechanical means for combining the depositedcoating material with material of the substrate to form a morehomogenous coating-substrate interface. Depositing and stirring can beperformed simultaneously, or in sequence with or without a period oftime in between. Depositing and stirring can also be performed with asingle tool or separate tools, which are the same or different.

Particular methods include depositing a coating on a substrate usingfrictional heating and compressive loading of a coating material againstthe substrate, whereby a tool supports the coating material duringfrictional heating and compressive loading and is operably configuredfor forming and shearing a surface of the coating.

In embodiments, the tool and coating material preferably rotate relativeto the substrate. The tool can be attached to the coating material andoptionally in a manner to allow for repositioning of the tool on thecoating material. Such embodiments can be configured to have nodifference in rotational velocity between the coating material and toolduring use. The coating material and tool can alternatively not beattached to allow for continuous or semi-continuous feeding ordeposition of the coating material through the throat of the tool. Insuch designs, it is possible that during use there is a difference inrotational velocity between the coating material and tool during thedepositing. Similarly, embodiments provide for the coating material tobe rotated independently or dependently of the tool.

Preferably, the coating material is delivered through a throat of thetool and optionally by pulling or pushing the coating material throughthe throat. In embodiments, the coating material has an outer surfaceand the tool has an inner surface, wherein the outer and inner surfacesare complementary to allow for a key and lock type fit. Optionally, thethroat of the tool and the coating material are capable of lengthwiseslideable engagement. Even further, the throat of the tool can have aninner diameter and the coating material can be a cylindrical rodconcentric to the inner diameter. Further yet, the tool can have athroat with an inner surface and the coating material can have an outersurface wherein the surfaces are capable of engaging or interlocking toprovide rotational velocity to the coating material from the tool. Inpreferred embodiments, the coating material is continuously orsemi-continuously fed and/or delivered into and/or through the throat ofthe tool. Shearing of any deposited coating material to form a newsurface of the substrate preferably is performed in a manner to disperseany oxide barrier coating on the substrate.

Yet another aspect of the present invention is to provide a method offorming a surface layer on a substrate, which comprises filling a holein a substrate. The method comprises placing powder of a fill materialin the hole(s), and applying frictional heating and compressive loadingto the fill material powder in the hole to consolidate the fillmaterial.

A further aspect of the invention provides a method of making consumablerod stock. The method comprises placing powder of a coating material ina die, applying frictional heating and compressive loading to thecoating material powder in the die to consolidate the coating material,and recovering a rod comprising the consolidated coating material.

These and other aspects of the present invention will be more apparentfrom the following description. The features and advantages of thepresent invention will be apparent to those skilled in the art. Whilenumerous changes may be made by those skilled in the art, such changesare within the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These drawings illustrate certain aspects of some of the embodiments ofthe present invention, and should not be used to limit or define theinvention.

FIGS. 1A-C are schematic illustrations of various embodiments offriction-based tools according to the invention comprising variousshaped throats or interiors.

FIGS. 2A and 2B schematically illustrate an exemplary process fordepositing coating material on a substrate using tooling with a squarethrough hole configuration.

FIGS. 3A-G are schematic illustrations demonstrating various surfacegeometries for the shearing shoulder of exemplary tools of theinvention.

FIG. 4 schematically illustrates a friction-based fabrication process inaccordance with an embodiment of the present invention.

FIG. 5 is a photograph illustrating an exemplary method and tooling ofthe invention for applying a 6061 Al coating to a 6061 Al substrate.

FIGS. 6A-D schematically illustrate a friction-based fabrication processin accordance with an embodiment of the present invention.

FIGS. 7A-F schematically illustrate a friction-based hole repair methodin accordance with an embodiment of the present invention.

FIGS. 8A-8D schematically illustrate a method of making a consumable rodin accordance with an embodiment of the present invention.

FIGS. 9A and 9B are photomicrographs of a 5083 Al/6063 Al—SiC (10 vol.%) FSF sample, showing the substrate, friction-based fabricated coating,and interfacial region.

FIG. 10A is a photomicrograph illustrating a typical coating producedaccording to embodiments of the invention showing a transversemicrostructure of 5083 Al.

FIG. 10B is a schematic illustrating orientation of the micrograph ofFIG. 10A with respect to relative translation.

FIG. 11 illustrates optical photomicrographs of Al—SiC MMC coating. Thetop micrograph illustrates the entire transverse section and the bottommicrographs illustrate higher magnification micrographs of the specificlocations shown by the squares.

FIG. 12 illustrates an SEM image of the 6061 Al—SiC MMC microstructureindicating banding.

FIG. 13A is a photomicrograph of a 6061 Al coating on a 6061 Al barprepared in accordance with tooling and methods of the presentinvention.

FIG. 13B is a photomicrograph of a Ni/Al bronze coating on a Ni/Albronze casting prepared with tooling and methods of embodiments of thepresent invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

The present invention is directed to the field of friction-basedfabrication. More particularly, the present invention relates tocoating, surface modification and repair of substrates usingfriction-based fabrication tools, to techniques and tool configurationsfor performing such processes, and to the production of such tools.Friction-based fabrication tools of embodiments of the invention includeconfigurations capable of imparting frictional heating, compressiveloading, and/or mechanical stirring of the coating material and/orsubstrate material during processing to allow for the coating materialto be applied, adhered, deposited, and/or intermixed with the materialof the substrate to form a coating on the substrate. As discussed indetail below, the present invention allows for the use of differentcoatings providing improved results in the applications in which theyare sometimes used.

It is noted that in the examples and description provided in thisapplication, various modifications can be made and are also intended tobe within the scope of the invention. For example, the described methodscan be practiced using one or more of the method steps described, and inany order. Further, method steps of one method may be interchangedand/or combined with the steps of other methods described and/or withmethod steps known to those of ordinary skill in the art. Likewise, thefeatures and configurations for particular tooling described in thisapplication may be omitted, interchanged, and/or combined with otherfeatures described or known to those of ordinary skill in the art. Evenfurther, tooling to obtain certain results or to perform specific stepsof methods described in this application is also included in the scopeof the invention even though the particular details of such tools aredescribed relative to performing method steps instead of the toolsthemselves.

Very generally, embodiments of the present invention are directed totooling and techniques for friction-based fabrication of metalsubstrates. Such techniques include applying coating materials to asubstrate by forming a surface layer on a substrate, eg, by depositing acoating on a substrate using frictional heating and compressive loadingof a coating material against the substrate, whereby a tool supports thecoating material during frictional heating and compressive loading andis operably configured for forming and shearing a surface of thecoating.

Such methods can include depositing a coating material on a substratewith frictional heating and compressive loading of the coating materialagainst a surface of the substrate; and spreading the coating materialacross the substrate by translating, relative to one another, a tool andthe substrate, wherein the tool comprises a shoulder for trapping andshearing coating material below the shoulder.

Even further, general methods of forming a surface layer on a substratecan include depositing a coating material on a substrate by pressing andtranslating the coating material against and across the substrate whilerotating the coating material with a tool which causes frictionalheating of the coating material and substrate.

Friction-based fabrication tooling for performing such methods arepreferably designed or configured to allow for a consumable coatingmaterial to be fed through or otherwise disposed through an internalportion of a non-consumable member, which may be referred to as athroat, neck, center, interior, or through hole disposed throughopposing ends of the tool. This region of the tool can be configuredwith a non-circular through-hole shape.

As shown in FIGS. 1A-1C, various interior geometries for the tooling arepossible. With a non-circular geometry, shown in FIGS. 1A and 1B, theconsumable filler material is compelled or caused to rotate at the sameangular velocity as the non-consumable portion of the tool due to normalforces being exerted by the tool at the surface of the tool throatagainst the feedstock. Such geometries include a square through-hole(FIG. 1A) and an elliptical through-hole (FIG. 1B) as examples. Inconfigurations where only tangential forces can be expected to beexerted on the surface of the filler material by the internal surface ofthe throat of the tool, the feed stock will not be caused to rotate atthe same angular velocity as the tool. Such an embodiment is shown inFIG. 1C, where a circular geometry for the cross-section of the tool incombination with detached or loosely attached feedstock, would beexpected to result in the coating material and tool rotating atdifferent velocities.

More specifically, the magnitude of force transferred from the rotatingtool to the filler material is dependent on the coefficient of frictionbetween the two. Thus, if the coefficient of friction is significantlylow and the inertial force required to induce rotation of the fillermaterial is significantly high, then the tool can rotate withoutinducing rotation (or with inducing rotation at a lower speed than thetool) in the cylindrical filler material. Under some circumstancesduring operation, differences in rotational velocity between the tooland the filler or coating material within the tool can lead to somecoating material being deposited inside the tool, an accumulation ofwhich can be problematic. Having the specific interior tool geometriesdescribed in this application can reduce this issue, such asappropriately sized square-square or elliptical-elliptical shapedfiller-dispenser geometries. Another way of reducing the difference inrotational velocity between the tool and the filler material is tomanufacture coating material rods that will fit tightly within thethroat of the tool, or to otherwise tightly pack the filler materialinto the throat of the tool.

Any shape of the cross section of the interior of the tool that iscapable of exerting normal forces on a coating material within the toolcan be used. The throat surface geometry and the filler materialgeometry can be configured to provide for engagement and disengagementof the tool and coating material, interlocking of the tool and feedmaterial, attachment of the tool and feed material, whether temporary orpermanent, or any configuration that allows for the filler material todependently rotate with the tool.

The interior surface shape of the tool (the throat) and thecorresponding shape of the filler material may not be critical and canbe constructed in a manner suitable for a particular application. Shapesof these surfaces can include, but are by no means limited to, square,rectangular, elliptical, oval, triangular, or typically any non-circularpolygon. Additional shapes may include more distinctive shapes such as astar, daisy, key and key-hole, diamond, to name a few. Indeed, the shapeof the outside surface of the filler material need not be the same typeof shape as the surface of the throat of the tool. For example, theremay be advantages from having a filler material rod with a squarecross-section for insertion into a tool throat having a rectangularcross-section, or vice-versa where a filler material rod having arectangular cross-section could be placed within a tool throat having asquare cross-section in which the corners of the filler material rodcould contact the sides of the square throat instead of sides contactingsides. Particular applications may call for more or less forces to beexerted on the coating material within the throat during operation ofthe tool. With concentric shapes and very close tolerance between thefiller material and the tool certain advantages may be realized.Additionally, different shapes may be more suitable for differentapplications or may be highly desired due to their ease of manufacturingboth the interior of the tool and corresponding filler material rods.One of ordinary skill in the art, with the benefit of this disclosure,would know the appropriate shapes to use for a particular application.

FIGS. 2A and 2B provide schematic drawings illustrating exemplarydimensions for tooling according to the invention as well as use of suchtooling in friction-based fabrication methods. Even though other shapesmay be used to achieve the results of this invention, exemplified inFIG. 2A is a tool with a square through hole. Even though it may bepreferred to configure feed material with the same shape and/or aslightly smaller size in diameter, the form of the consumable materialcan be of any form or shape, such as solid, powder, composite, solidtubes filled with powder, to name a few.

FIG. 2B shows how coating material can be deposited on a substrate usinga downward frictional force in combination with translational movementacross the surface of the substrate at a fixed distance. The fillermaterial is consumed by being forced toward and deposited on the surfaceof the substrate through the throat of the non-consumable tool usingrotation of the tool (and consequently the feed material) and otherrelative movement between the tool and the substrate such astranslational movement. The downward force can be imposed on the fillerrod for example by pulling or pushing the material through the throat ofthe tool. A preferred method is to push the rod with an actuator towardthe surface of the substrate. As shown, the use of a non-circularthrough-hole and corresponding shape of filler material may be oneexample of a way to compel the material in the tool to spin at the sameangular velocity as the tool. It has been found that rotational movementof the filler material may be desired for certain applications and thatno rotational movement between the filler material and inner geometry ofthe non-consumable portion of the tool be experienced during use.Further, it is desired that the filler material be operably configuredto move freely lengthwise through the tool so as to allow forsemi-continuous or continuous feeding of the material toward thesubstrate for a desired period of time.

The tooling in some embodiments comprises a shearing surface. Thissurface is used for shearing the surface of the coating material beingdeposited to form a new surface of the substrate. The shearing surfacecan be incorporated in the tool in a variety of ways, including toobtain tooling comprising a collar, spindle, anvil, cylindrical tool,shoulder, equipment, rotating tool, shearing tool, spinning tool, stirtool, tool, tool geometry, or threaded-tapered tool to name a few. Theshearing surface is defined more completely by its function, e.g., thesurface(s) of the tool capable of trapping, compressing, compacting orotherwise exerting at least a downward (ie, normal) force on the coatingmaterial deposited on the substrate and through the coating material tothe substrate.

For example, any known shearing surface geometry can be used includingthose described in UK Patent Application No. GB 2,306,366, which ishereby incorporated by reference herein in its entirety. Further, forexample, shoulder surface geometries of tools of the present inventioncan include the exemplary surface geometries shown in FIGS. 3A-G, whichare provided as examples only and are not intended to limit embodimentsof the invention. Other variations in the shearing surface are possibleand are included in the invention, such as modifications that may beapparent to those of ordinary skill in the art desired for particularapplications.

As shown in FIGS. 4 and 5 and in certain embodiments of the presentinvention, friction-based fabrication may be used to add new material tothe surfaces, thus modifying the surface compositions to addressmultiple application requirements. In embodiments, friction-basedfabrication may be a solid state, friction-based coating method that canbe used, for example, to meet naval needs for welding, coating andrepair of aluminum vessels. Friction-based fabrication according to theinvention uses shear-induced interfacial heating and plastic deformationto deposit wrought metal and/or metal matrix composite (MMC) coatings onsubstrates. FIGS. 4 and 5, which provide a photo and schematic drawingof a 6061 Al coating being applied to a 6061 Al substrate, illustrate anexemplary process of the invention.

In this friction-based fabrication process embodiment, thecoating/filler material (for example, solid bar or powder) can be fedthrough the rotating spindle where frictional heating occurs at thefiller/substrate interface due to the rotational motion of the fillerand the downward force applied. The mechanical shearing that occurs atthe interface acts to disperse any oxides or boundary layers, resultingin a metallurgical bond between the substrate and coating. As thesubstrate moves (or with any relative motion between the substrate andtool), the coating can be extruded under the rotating shoulder of thetool. FIG. 10A shows a typical coating transverse microstructure for5083 Al (coating and substrate) and its orientation relationship withrespect to the substrate and translation directions is shown in FIG.10B. Typical translation speeds are approximately 1-3 inches per minute,however, with particular tool design and/or materials being used, it ispossible that the translation speed could be increased to 10 inches perminute or faster.

One embodiment of the present invention provides a friction-basedcoating method otherwise referred to as friction-based fabrication, inwhich material is deposited onto a substrate and subsequently stirredinto the substrate using friction stir processing to homogenize andrefine the microstructure. Certain advantages of this solid-stateprocess include, but are not limited to, the capability of depositingcoatings, including nanocrystalline aluminum and/or metal matrixcomposites and the like, onto substrates such as aluminum at relativelylow temperatures. The capability to deposit the substrates at such lowtemperatures allows for the ability to use a broader range ofsubstrates, thereby being able to form improved friction stir tools formultiple applications. Coatings produced using friction-basedfabrication have other advantages, such as superior bond strength,density, and lower oxide content as compared to other coatingtechnologies in use today. The friction-based fabrication process mayalso be used to fill holes in various types of substrates, therebymaking them stronger. Also provided by embodiments of the invention aremethods of making rod stock.

MMC (metal-matrix composite) coatings can be formed in the same manneras a wrought coating, including by having the matrix alloy and thereinforcement feed through the spindle. However, the MMC consumable feedmaterials can be made by several methods, including but not limitedto: 1) the matrix metal and reinforcement powders can be mixed and usedas feed material or 2) a solid rod of matrix can be bored (e.g., tocreate a tube or other hollow cylinder type structure) and filled withreinforcement powder, or mixtures of MMC and reinforcement material. Inthe latter, mixing of the matrix and reinforcement can occur furtherduring the fabrication process.

FIG. 11 shows the microstructure of a 6061 Al—SiC MMC coating on a6061Al substrate produced by friction-based fabrication. In this case,the volume fraction (vol %) of SiC reinforcement is approximately15-20%. The micrographs show that SiC is homogenously distributed in thecoating and that there is no discrete interface between the matrix metaland substrate—continuity of the Al is maintained as the local volumefraction of SiC goes to zero.

FIG. 12 is an SEM image of 6061 Al—SiC MMC microstructure indicatingbanding.

The bond strength between the MMC coating and substrate was tested byfabricating a 0.5 inch tall Al—SiC(10 vol %) rib on a 5083 Al andmachining micro-tensile samples with the coating/substrate interface inthe middle of the gage section, a shown in FIGS. 12A-B and FIGS. 9A-B.Representative tensile stress-strain curves for the 5083 Al-6063 Al—SiC(10 vol %) interface sample along with the UTS for 6063 Al T1 are shownin FIGS. 12A-B.

The results of the bond strength test show that the coating/substratebond strength is equal to the UTS of the coating alloy and that thecoating exhibits significant ductility/toughness. Additionally, Vickersmacro-hardness testing indicated that 6063 Al FSF coatings with 10 vol %SiC increased the coating hardness from 47 MPa to 57 MPa, a 20% increasein hardness with only 10 vol % SiC.

Development of friction-based fabrication for Al alloys and MMCs hasdemonstrated the potential of the process to deposit wrought metalcoatings and extend the operating envelope for Al alloys in corrosiveand high-wear applications. Demonstrating MMC coatings with highinterfacial bond strength and improved hardness provides a firmfoundation for transitioning the technology to stronger, higher meltingtemperature materials, such as copper alloy CDA180 and 4340 steel.

Initial testing of FSF as a repair method for Ni—Al bronze casting wasconducted on material provided by NSWCCD. In this demonstration, Ni—Albronze was deposited by way of friction-based fabrication onto a Ni—Albronze casting. The results of the demonstration were promising in thata coating with refined microstructure was deposited and the interfacebetween the coating and substrate was diffuse in the processed region,as shown in FIG. 13B. As expected, the demonstration resulted in extremewear of the H13 tool steel processing tool. Demonstrations with Ni—Albronze with refractory tooling shows novel improvements.

According to embodiments of the invention, a friction-based fabricationmethod includes depositing a coating on a substrate using frictionalheating and compressive loading of a consumable material on an uppersurface of a substrate using one or more of the inventive toolsdescribed in this specification, and optionally further using additionalfriction stir processing to increase adhesion between the substrate andthe coating. In applications where the coating is deposited on thesubstrate and a period of time is allowed to elapse prior to furtherprocessing, it is desired that the deposition technique involveimparting sufficient interfacial adhesion between the coating andsubstrate, such that further friction stir processing does notdelaminate the coating from the substrate.

In embodiments, a coating material is deposited on a substrate usingfrictional heating and compressive loading of the coating materialagainst the substrate. The coating material is a consumable material,meaning as frictional heating and compressive loading are applied duringthe process, the coating material is consumed from its original form andis applied to the substrate. Such consumable materials can be in anyform including powders, pellets, rods, and powdered-filled cylinders, toname a few. More particularly, as the applied load is increased, beyondwhat would be required to join the consumable coating material to thesubstrate, and the portion of the coating material adjacent to thesubstrate is caused to deform under the compressive load. In preferredembodiments, the deformed metal is then trapped below a rotatingshoulder of the friction-based coating tool and then sheared across thesubstrate surface as the substrate translates and rotates relative tothe tool.

As shown in FIGS. 6-8, any of the tooling described in this application,and preferably the configurations demonstrated in FIGS. 1-8, isinterchangeable and applicable to numerous coating, repairing, filling,and building up type applications, including for repairing holes insubstrate surfaces, and for the manufacture of feedstock.

Such methods, for example, can include methods for friction-based coatedsubstrate fabrication comprising: (a) compressive loading of a coatingmaterial against a surface of a substrate using a tool with a shoulderand throat; (b) frictional heating of the coating material on thesubstrate surface using the tool, which has a throat shaped to exertnormal forces on the coating material disposed therein, to rotate thecoating material with the tool at an effective speed; (c) translation ofthe tool relative to the substrate surface; and (d) trapping the coatingmaterial against the substrate surface with the shoulder of the tool andshearing of the coating material to form and deposit a coating on thesubstrate surface. It is preferred that in embodiments the throat of thetool is shaped with a non-circular cross-sectional shape. Furtherdesired, are tooling wherein the throat of the tool is shaped to exertnormal forces on a solid, powder, or powder-filled tube type coatingmaterial disposed therein. Embodiments may also include features toensure the frictional heating and compressive loading are of a degreesufficient to enable mixing of dispensed coating material with materialof the substrate at a coating-substrate interface.

The tools, and/or the shearing surface(s) of the tools, can beconsumable, non-consumable, or a combination of both (eg, compriseconsumable and non-consumable portions or members). Typically, theshoulder of the tool comprises a substantially flat surface geometry,such as the rotating collar shown in FIG. 6A, the stirring tool of FIG.7D, and the upper anvil of FIG. 8A. Alternatively, the tools of thepresent invention can comprise a stepped surface geometry, pin-typesurface, surface with one or more protrusions (such as the stir toolshown in FIG. 6D), or any surface geometry capable of delivering thedesired amount of mechanical and/or frictional interaction with thesubstrate material and/or the coating material for a desiredapplication.

More particularly, as shown in FIGS. 6A-D, schematic diagrams areprovided to illustrate an exemplary method according to embodiments ofthe invention. FIGS. 6A-C illustrate one mode of deposition of a coatingmaterial onto a substrate. Even though the coating material in thisembodiment is shown as a solid rod in cylindrical form, the consumablecoating material can be in any number of forms, including powder,pellet, or fillable cylinders. Likewise, any interior geometry of thetool (ie, the throat geometry) can be used. Preferably, the consumablecoating material will have one shape and the throat will have acomplementary shape, such as both having correspondingly shaped andsized square cross sections, such as square-square cross sections.

Metallurgical bonding and/or homogenization and/or refinement of themicrostructure between the substrate and coating can be achieved throughrotation and/or translation or other relative movement between the tooland substrate. Such relative movement between substrate and tool,combined with means for compressing and retaining the coating materialbetween the substrate and tool, can add additional frictional heating tothe system. Likewise, the surface geometry of the tool can be modifiedto provide increased frictional processing of the materials, such as atool with one or more pin-type projections, or a separate friction stirtype tool. Frictional heating, compressive loading, and mechanicalstirring are factors that can be adjusted to achieve a particularresult.

More particularly, a tool embodiment as shown in FIG. 6A can comprise acollar or other non-consumable portion of the tool capable of beingattached to a rod or other consumable portion. Typically, in such aconfiguration, the collar is ideally releasably engagable with theconsumable rod. In this manner, as the coating material is consumed onthe surface of the substrate, the collar can be repositioned on thematerial to provide for additional material to be deposited. Attachmentof the coating material and non-consumable portion is preferred so thatthe coating material is caused to rotate at the same speed orsimultaneously with the non-consumable portion of the tool. Thisfunction can be achieved in any number of ways, including by shaping theconsumable portion of the tool as a rod having the same shape and sizeas the cross section of the throat of the non-consumable portion. It isrecognized that some shape or size difference may be desired so that theconsumable portion is capable of easily being inserted into the throatof the tool. If the cross sections of the two members are the same sizeand shape insertion and lateral movement through the throat may bedifficult. Using similarly shaped and sized members, rotation of thenon-consumable portion of the tool will cause normal forces to beimparted on the consumable portion present in the throat of the tool.Such normal physical forces will subsequently cause the internal member(consumable member) to rotate with the external member (non-consumablemember).

To provide an amount of consumable coating material available fordeposition on the substrate, in preferred embodiments it may be desiredto leave approximately 3 mm of the rod beneath the collar or othershearing surface of the tool, or other volume of space applicable forobtaining a desired thickness of coating. As shown in FIG. 6B, this 3 mmsection of the consumable portion of the tool can be pressed onto thesubstrate to a desired level of compressive loading, usually determinedby the type of coating material being used. With the consumable andnon-consumable portions of the tool physically secured together, eitheror both members can be pressed toward the substrate to cause the coatingmaterial to be deposited on the substrate. In this embodiment, rotationof the tool and substrate is also included. This relative movementbetween the substrate and the tool increases frictional heating of theoverall system to facilitate deposition of the coating material on thesurface of the substrate between the tool and the substrate.

As shown in FIG. 6C, if the collar or other shearing surface of the toolis maintained at a fixed distance from the upper surface of thesubstrate during processing, the coating material is spread evenlyacross the surface of the substrate.

Further homogenization, refinement, and increased interlayer adhesioncan be accomplished using friction stir processing, as shown in FIG. 6D.For example, once the coating has been deposited onto the surface of thesubstrate, e.g., using the solid-state friction deposition method, itmay then be friction stir processed to adhere the coating to the surfaceof the substrate and refine the coating microstructure. The goal of thefriction stir process may be to produce a homogenous coating with a bondstrength approaching the ultimate tensile strength of the base alloy.The quality of the friction stirred regions of the substrates may beoptimized, including eliminating any defects or channels present alongthe length of the friction stir path. Elimination of the channel(s) maybe achieved by using a friction stir tool with a threaded pin. Bymodifying the tool geometry, coated substrates may be produced withoutchannels through the use of a threaded-tapered tool. Additional frictionstir processing can be performed immediately after deposition, a periodof time following deposition, or substantially simultaneously withdeposition. The additional friction stir processing can be performedwith a different tool having a desired geometry to accomplish aparticular purpose. Indeed, a flat surface geometry of the tools willprovide an amount of friction stir processing, while, increasing thesurface area of the shearing surface of the tool with projections orother protruding structure(s) will provide additional friction stircapabilities and benefits. The coating deposited on the surface of thesubstrate can be achieved by using a single layer of deposited coatingmaterial or multiple layers applied until the desired coating thicknessis achieved.

The coating material, in some embodiments, can be deposited andprocessed on the substrate in nanocrystalline form. As used herein, theterm “nanocrystalline” means a material in which the average crystalgrain size is less than 0.5 micron, typically less than 100 nanometers.Due to the fact that the friction-based fabrication process is carriedout at a relatively low temperature below the melting point of thecoating material, little or no crystal grain growth occurs during theprocess and the nanocrystalline structure of the coating material may bemaintained in the coating as applied to the substrate.

In accordance with another embodiment of the present invention, thecoating material comprises a metal matrix composite (MMC). As usedherein, the term “metal matrix composite” means a material having acontinuous metallic phase having another discontinuous phase dispersedtherein. The metal matrix may comprise a pure metal, metal alloy orintermetallic. The discontinuous phase may comprise a ceramic such as acarbide, boride, nitride and/or oxide. Some examples of discontinuousceramic phases include SiC, TiB₂ and Al₂O₃. The discontinuous phase mayalso comprise an intermetallic such as various types of aluminides andthe like. For example, titanium aluminides such as TiAl and nickelaluminides such as Ni₃Al may be provided as the discontinuous phase. Themetal matrix may typically comprise Al, Cu, Ni, Mg, Ti, Fe and the like.

To produce Al—SiC metal matrix composite coatings, aluminum tubes may befilled with silicon carbide powder and used as coating rods. The filledtubes may yield an Al—SiC coating, but the volume fraction of thereinforcement may vary locally. However, for precise volume fractioncontrol, homogenous metal matrix composite rods containing theappropriate volume fraction may be used instead of powder filled tubes.

Reinforcement of the metal matrix composite coating may be incorporatedinto the matrix by traditional blending techniques or grown in-situ fromelemental metals with reaction synthesis. Table 1 lists MMC systems, eg,which can be formed by reaction synthesis.

TABLE 1 Reaction Synthesis of In-situ MMCs Using FSF Ti + xAl → TiAl +(x − 1)Al (Aluminum matrix with TiAl reinforcement) 3Ni + yAl → Ni₃Al +(y − 1)Al (Aluminum matrix with Ni₃Al reinforcement) 2B + zTi → TiB₂ +(z − 1)Ti (Titanium matrix with TiB₂ reinforcement) Ti + wNi → NiTi + (w− 1)Ni (Nickel matrix with NiTi reinforcement)

In reaction synthesis, elemental metals react due to the thermal and/ormechanical energy imparted during processing to form intermetallic orceramic particulates. The rotation of the tool and feed materialrelative to the substrate may generate frictional heat which raises thetemperature of the elemental constituents to that at which the reactioncan initiate. As the reactions of elemental metals used for reactionsynthesis are exothermic, additional heat is evolved in the formation ofthe intermetallic particles. An aspect of using friction-basedfabrication to form in-situ MMC coatings is the fact that the shearingof the metal by the tool and rotation of the feed material cracks anddisperses the oxide barrier coatings, which exist on all metal exposedto oxygen, providing a high concentration of the metal-to-metal contactrequired for the reaction to occur. In such reaction synthesis, thereacting metal may be provided from the substrate and the feed metal, orall of the reacting metals could be provided from the feed material.

In-situ MMCs may exhibit enhanced mechanical properties as compared toMMCs formed ex-situ, i.e., by blending the matrix and reinforcement.In-situ formation of MMCs yields relatively small single crystalreinforcements, which are thermodynamically stable in the matrix.In-situ formation results in clean, unoxidized particles, and theinterfacial strength between the reinforcement and matrix may be higherthan that of ex-situ MMCs.

Various types of substrates may be coated using the friction-basedfabrication process of the present invention. For example, metalsubstrates comprising Al, Ni, Cu, Mg, Ti, Fe and the like may be coated.Furthermore, polymers and ceramics may be provided as the substrate. Forexample, the substrate may comprise a thermoplastic material.

In accordance with an embodiment of the present invention, the coatingmaterial may be deposited on the substrate at a temperature below amelting temperature of the coating material. The depositing (eg,loading) of the coating material can be performed using one or moremethod steps for example described above. Loading of the coatingmaterial onto the substrate may be performed at a temperature rangingfrom about 100 to 500° C. or more below the melting point of the coatingmaterial. When the coating material comprises Al, the material may bedeposited on a substrate at a temperature below about 500° C., typicallybelow about 400° C. Once the coating material is initially loaded ontothe substrate, any subsequent friction stirring of the coating materialand/or substrate material may also preferably be performed below themelting temperature of the coating material. For example, when thecoating material comprises Al, friction stirring temperatures may bemaintained below about 500° C., typically below about 400° C.Furthermore, the friction stirring process(es) may be performed at atemperature below a melting temperature of the substrate.

Another embodiment of the metal deposition method may significantlyreduce the labor and time requirements. For example, the coatingmaterial to be deposited on the substrate may be delivered to thesubstrate surface using a “push” method, where a rotating-plunging toolpushes the filler material (such as a rod of finite length or aninfinite amount of powder filler material can be fed into the tool body)through the rotating tool, such as a spindle. The spindle may be rotatedindependently using an additional motor while the milling machinerotates the plunging tool. As the spindle and plunging tool rotate,compressing loading and frictional heating of the filler material can beaccomplished by pressing the coating material into the substrate surfacewith the downward force (force toward substrate) and rotating speed ofthe plunging tool. This design allows a large volume of raw material tobe fed to the substrate surface as compared to manual methods. As therod material may be spread onto the substrate, the plunging toolcontinues to feed more filler rod through the spindle onto thesubstrate. With machine design improvements, the length of rod stock maybe increased.

This “push” method may be a feasible solution to the filler rod deliverychallenge, but in the interest of processing speed and volume could befurther improved upon. For continuous deposition, a “pull” method, wherethe spindle rotation pulls the rod into the spindle, may be employed sothat the rod length can be increased and the rods can be fedcontinuously. Other means for continuous feeding (continuously addingnew material to the tool) or continuous deposition (continuous deliveryof feedstock to the substrate) can be used. For example, using afeedstock in powdered or pellet form would allow for continuous feedingand continuous deposition of the coating material in and through thetool (ie, an infinite amount of feed material can be introduced to anddeposited by the tool for an infinite period of time). Semi-continuousdeposition through the tool may involve use of a rod to push theexisting material (whether powder, pellet, or rod form) in the throat ofthe tool out and toward the substrate surface, whereby only the materialin the tool can be used. Using such semi-continuous processes andtechniques, the process is typically stopped periodically to add newmaterial to the system.

Other continuous or semi-continuous methods for delivering the coatingmaterial to a surface of a substrate also exist, including using athreaded member to push or pull feedstock through the tool. For example,feedstock may be pulled into the throat or neck of the tool using aninternally threaded section on the inner diameter of the spindle throat.Any type feedstock can be used, but a solid feedstock rod-typeconfiguration is preferred to powder or pellet forms, but such forms arealso capable of being pulled or pushed into the tool using one or moremeans for exerting a downward force on the material. During thedeposition process, the spindle rotates at a slightly slower rate thanthe rotating rod stock. Due to the difference in rotational velocities,the threaded portion of the neck pulls the rod through the spindle andforces the metal under the rotating shoulder. The threads impart a forceon the feedstock that pushes the feed material toward the substrate muchlike a linear actuator or pneumatic cylinder or other mechanical forcepushing on a surface of the feedstock would.

The difference in rotational velocity between the rod and the spindle,coupled with the pitch of the internal threads in the spindle, woulddetermine the coating deposition rate. It may be desired to activelycontrol the temperature of the rod inside and outside the spindle sothat the thermally induced softening of the filler rod is not totallydependent on frictional heating. Thermal control provides means toincrease deposition rates to meet application requirements.

Yet another embodiment of the present invention provides a method ofrepairing holes in substrates, and a way to modify the local propertiesof a substrate. A hole repair method is illustrated in FIGS. 7A-F. Asshown in FIG. 7A, the repair process begins with a substrate having ahole of known diameter. If the hole is not circular in cross-section orhas an unknown or undesired diameter, it may be machined to create ahole equal to the diameter of the tool used in FIG. 7D. As shown in FIG.7B, if the hole is a through-hole, it may be necessary to apply abacking plate, e.g., composed of either the substrate material or thefiller material. The backing plate serves as a base for the frictionprocessing to follow, and may be inset into the lower surface of thesubstrate if desired. As shown in FIG. 7C, a layer of loose powder isdeposited into the hole, and subsequently processed using compressiveloading and frictional heating into the backing plate or the bottom ofthe hole, as shown in FIG. 7D, with a tool subsequently equal indiameter to that of the hole. FIG. 7E illustrates the resultant layer ofmaterial added to the bottom of the hole. FIG. 7F illustrates thedeposition of more loose powder into the hole, which may be processed asshown in FIG. 7D. This process may be repeated until the hole is filled.As the depth of the fill approaches the top of the substrate, flashmaterial may accumulate around the surface of the hole. Once the filldepth reaches the substrate surface, the flash material may be cut awayleaving a smooth surface.

The hole-repair method may be used to modify the properties of asurface. A series of holes with any given depth may be drilled into asubstrate and then re-filled, using the hole-repair method, with amaterial having the desired local properties, thereby selectivelymodifying the local properties of the substrate. With multiple toolsacross the work volume, the processing time for an entire work piece maybe reduced, and the ability to selectively vary the local microstructuremay be readily accomplished. The processing time may be furtherdecreased, by employing as the multiple tools, tools capable ofautomated delivery of the coating/filler material, for example, the pushor pull methods described above.

Because material flexibility may be possible using the present process,the desired alloys and material volume fractions are not always readilyavailable in the rod stock form needed for the raw material. As such, anaspect of the present invention may be to provide a stock fabricationmethod that uses powder as its raw material. This stock fabricationmethod provides the ability to produce cylindrical rods from a widevariety of materials and composites in various volume fractions.Further, in contrast to the cold spray coating method, thisfriction-based stock fabrication method may be able to process highaspect ratio particles, such as those produced through cryomilling,which allows for the inexpensive construction of nanocrystalline rodsfor deposition by friction-based fabrication.

A variation of the hole filling method may be used for production of rodstock to supply the solid-state friction deposition process describedabove. Because the hole filling method utilizes powder as its rawmaterial, limitless material and volume fraction flexibility exists forproduction of rods and cylinders by this method. For example, thecomposition of the rod stock may be graded along its length, in whichcase coatings made from the rod during the friction-based fabricationprocess may have different compositions and properties which varygradually from one area of the coating to another, e.g., one area of thecoating may have relatively high hardness while another area may haverelatively high corrosion resistance. To deposit advanced materials suchas nanocrystalline aluminum and/or aluminum MMCs using thefriction-based fabrication process, rod stock of these materials withpredictable and repeatable volume fractions is desired. As theseadvanced materials are not commercially available in rod form, thepresent low-pressure high-shear powder compaction (LPHSPC) process, asshown in FIGS. 8A-8D, may be used to provide rods of coating materialsfor the friction-based fabrication process.

In one embodiment, LPHSPC may be accomplished by manually depositingapproximately 0.25 g of powder into a cylindrical cavity, asschematically shown in FIG. 8A, and then manually applying a downwardcompaction force with a spinning cylindrical tool, as shown in FIG. 8B.As shown in FIGS. 8C and 8D, the powder deposition and processing stepsare repeated. The downward pressure and shear from the tool compact thepowder and adhere it to the previous layer. Fully dense sections of,e.g., ⅜ and ½-inch diameter, rods may be fabricated frommicrocrystalline and nanocrystalline aluminum powders using the manualmethod. However, rods of significant length may be fabricated byautomated methods for use as feed stock for friction-based fabricationsystems. Thus, constructing an automated low-pressure high-shear powdercompaction unit may be desirable.

To supplement the above disclosure, additional examples are providedbelow. These examples are intended to illustrate various aspects of theinvention, and are not intended to limit the scope of the invention.

Different deposition geometries are used to test the bond strengthbetween 5083 Al and a ½ inch deposit of nanocrystalline Al (7 w % Mg,cryomilled 4 hrs); and test the bond strength between 5083 Al and a ½inch deposit of 6063 Al—SiC (10 v %). Small tensile specimens were cutsuch that the 5083 Al substrate and the coating (nanocrystalline Al orAl—SiC) each composed half of the specimen and the interface planebetween the coating and substrate was in the middle of the gauge length,normal to the loading direction.

Friction-based fabrication was used to coat 2519 and 5083 Al substrates:

2519 and 5083 Al plates with Al—SiC surface layers: the Al—SiC coatingwas comprised of 6063 Al and approximately 10 v % SiC powder (1 mmaverage particle size);

A 2519 Al plate with a copper-free surface to enhance the corrosionresistance—the copper-free coating was made from 6063 Al;

A 5083 Al plate with a nanocrystalline Al deposit to enhance the impactresistance: the nanocrystalline Al alloy contained 7 w % Mg, and wascryomilled for 4 hours;

A half-inch, curved Al—SiC rib on a 5083 Al plate: the rib was composedof 6063 Al and approximately 10 v % SiC powder (1 mm average particlesize); and

Repair of a 1-inch diameter hole in a 5083 Al plate without adverselyaffecting the plate microstructure: the material used was eithercommercially pure Al or nanocrystalline Al (due to machine limitations,the diameter of the hole was reduced to ½ inch).

Factors that influence the process' deposition rate are translationspeed, tool diameter, layer thickness, and delays resulting from manualprocesses. The angular velocity of the spindle is an important variablefrom the perspective of frictional heating and deposition quality, butdoes not directly factor into the deposition rate unless poor depositionquality leads to necessary rework. Once the acceptable angular velocityrange for the spindle is established for a given coating material, thisvariable will no longer have an impact on the deposition rate but couldbe used to manipulate the frictional heat input and thus the structureand properties of the coating. The deposition efficiency of thefriction-based fabrication process is nearly 100%. Material waste(scrap) in the process occurs only when machining flash at the edge ofthe processed region. This waste can be minimized or eliminated in anumber of ways, including process and product design.

A spindle capable of continuous deposition will eliminate manualintervention and setup delays, and allow material to be continuously fedthrough the spindle to the substrate surface. For continuous deposition,the material deposition rate will be equal to the product of thetranslation speed, shoulder diameter, and layer thickness.

Friction-based fabrication may be an effective and potentially efficientmethod of producing a variety of aluminum-based, copper-based, and othercoatings. Using simplistic deposition equipment, the process is able toproduce coatings, from advanced materials in the solid-state, with atleast twice the bond strength of the most competitive coatingtechnology. In addition, a wide variety of feed stock can be fabricatedusing the powder compaction process, allowing for wide-ranging materialflexibility in coatings. It may be desirable to provide an automatedcoating unit that can perform reproducibly over a wide range of processparameters and is capable of in-situ process monitoring. Consistentperformance and the ability to monitor spindle speed, torque, anddeposition temperature will afford the ability to detail the linkbetween the process and the coating structure and properties.

The present invention has been described with reference to particularembodiments having various features. It will be apparent to thoseskilled in the art that various modifications and variations can be madein the practice of the present invention without departing from thescope or spirit of the invention. One skilled in the art will recognizethat these features may be used singularly or in any combination basedon the requirements and specifications of a given application or design.Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention. It is intended that the specification and examples beconsidered as exemplary in nature and that variations that do not departfrom the essence of the invention are intended to be within the scope ofthe invention.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of the present invention. While compositions and methods aredescribed in terms of “comprising,” “containing,” or “including” variouscomponents or steps, the compositions and methods can also “consistessentially of” or “consist of” the various components and steps. Allnumbers and ranges disclosed above may vary by some amount. Whenever anumerical range with a lower limit and an upper limit is disclosed, anynumber and any included range falling within the range is specificallydisclosed. In particular, every range of values (of the form, “fromabout a to about b,” or, equivalently, “from approximately a to b,” or,equivalently, “from approximately a-b”) disclosed herein is to beunderstood to set forth every number and range encompassed within thebroader range of values. Also, the terms in the claims have their plain,ordinary meaning unless otherwise explicitly and clearly defined by thepatentee. Moreover, the indefinite articles “a” or “an,” as used in theclaims, are defined herein to mean one or more than one of the elementthat it introduces. If there is any conflict in the usages of a word orterm in this specification and one or more patent or other documentsthat may be incorporated herein by reference, the definitions that areconsistent with this specification should be adopted.

The invention claimed is:
 1. A friction-based fabrication toolcomprising: a non-consumable member having a body and a throat; aconsumable coating material; wherein the throat is shaped to exert anormal force on the consumable coating material disposed therein forimparting rotation to the coating material from the body when rotated ata speed sufficient for imposing frictional heating of the coatingmaterial against a substrate; wherein the throat contacts the entirelength of the portion of the consumable coating material that isdisposed in the throat; wherein the body is capable of dispensing andcompressive loading of the coating material from the throat onto thesubstrate and is capable of rotating and translating the body relativeto the substrate; and wherein the body comprises a surface for trappingcoating material loaded on the substrate in a volume between the bodyand the substrate and for forming and shearing a surface of a coating onthe substrate.
 2. The tool of claim 1, wherein the throat of thenon-consumable member is shaped with a non-circular cross-sectionalshape.
 3. The tool of claim 2, wherein the non-circular cross-sectionalshape is a square, rectangle, ellipse, oval, triangle, non-circularpolygon, star, daisy, key, or diamond.
 4. The tool of claim 2, whereinthe throat of the non-consumable member is shaped to exert normal forceson a solid, powder, or powder-filled tube type coating material disposedtherein.
 5. The tool of claim 1, wherein the throat of thenon-consumable member is shaped to exert normal forces on a plurality ofsurfaces of a consumable coating material disposed therein.
 6. The toolof claim 5, wherein the throat of the non-consumable member is shaped toexert normal forces on four or more surfaces of a consumable coatingmaterial disposed therein.
 7. The tool of claim 1, wherein theconsumable coating material and the throat have complementary shapes. 8.The tool of claim 7, wherein the consumable coating material and thethroat have correspondingly shaped and sized cross sections along theentire length of the portion of the consumable coating material that isdisposed in the throat.
 9. The tool of claim 8, wherein the consumablecoating material and the throat each have a square cross section. 10.The tool of claim 1, wherein the throat and the consumable coatingmaterial have a geometry configured to provide for engagement anddisengagement of the tool and the consumable coating material.
 11. Thetool of claim 1, wherein the throat and the consumable coating materialhave a geometry configured to provide for interlocking of the tool andthe consumable coating material.
 12. A friction-based fabrication toolcomprising: (a) a non-consumable member having a body and a throat;wherein the throat is shaped to exert a normal force on a consumablecoating material along the entire length of the portion of theconsumable coating material disposed therein for imparting rotation tothe coating material from the body when rotated at a speed sufficientfor imposing frictional heating of the coating material against asubstrate; wherein the body is capable of dispensing and compressiveloading of the coating material from the throat onto the substrate andis capable of rotating and translating the body relative to thesubstrate; and wherein the body comprises a surface for trapping coatingmaterial loaded on the substrate in a volume between the body and thesubstrate and for forming and shearing a surface of a coating on thesubstrate; and (b) a consumable coating material with a cross-sectionalong the entire length of the consumable coating material that has thesame shape as a cross-section of the throat.
 13. The tool of claim 12,wherein during use the throat of the non-consumable member contacts thecoating material along the entire length of the portion of the coatingmaterial that is disposed in the throat.
 14. The tool of claim 12,wherein the throat of the non-consumable member is shaped with anon-circular cross-sectional shape.
 15. The tool of claim 14, whereinthe non-circular cross-sectional shape is a square, rectangle, ellipse,oval, triangle, non-circular polygon, star, daisy, key, or diamond.